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Space ?

  1. Apr 22, 2010 #1
    This may be a dumb question . My friend asked me is there a place in space where there is no energy .And then he said
    is there a place in space where you can't see any stars . Do gravitational fields have energy densities .
    So is there a place in space that has no energy ?
  2. jcsd
  3. Apr 22, 2010 #2
    You can't test whether or not a region is devoid of energy. As soon as you measure something, you add energy to it. If you can't test a theory, it's not scientific.
  4. Apr 22, 2010 #3
    If I am observing a star through a telescope, how am I adding energy to that star?
  5. Apr 22, 2010 #4
    if you think about the size of your eye's iris, and the amount of starlight that enters it on a cloudless night, then think that some star light (energy) is also passing through just about every millimeter of space. Space isn't at absolute zero either.
  6. Apr 22, 2010 #5
    You're definitely interacting with the star when the light hits your eye. Maybe I'm playing fast and loose, equating "space" with "system".

    If you're taking a measuring on a region of space (and not a system of particles), you have the additional difficulty that your measurement must be made instantaneously. By naming spacial bounding box for a region in your coordinate system, you can specify what "space" you're talking about. But an instant later, it's unclear whether or not the same bounding box refers to the "same space".
  7. Apr 22, 2010 #6
    so then energy is everywhere.
  8. Apr 24, 2010 #7
    If energy is everywhere , and space is expanding , then where does this energy come from to fill the void .
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